IMAGING LENS

• US 20150323763A1
• Filed: 11/05/2014
• Published: 11/12/2015
• Est. Priority Date: 05/12/2014
• Status: Active Grant

• Current Assignee: Tokyo Visionary Optics Company Limited
• Original Assignee: Kantatsu Company Limited (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Yuza, Shingo
• Granted Patent: US 9,417,432 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G02B 13/0045 having five or more lenses
• CPC Class Codes: G02B 13/06 Panoramic objectives; So-called "sky lenses" including panoramic objectives having reflecting surfaces
• CPC Class Codes: G02B 13/18 with lenses having one or more non-spherical faces, e.g. for reducing geometrical aberration G02B13/002 takes precedence

Abstract

An imaging lens includes, in order from an object side, a first positive lens having a convex object-side surface, a second negative lens having a concave image-side surface, a third positive double-sided aspheric lens, a fourth positive lens having a convex image-side surface, and a fifth negative double-sided aspheric lens having a concave image-side surface, wherein the fifth lens image-side surface has pole-change points off an optical axis; and conditional expressions below are satisfied:

0.80<ih/f<1.00  (1)

0.6<TTL/2ih<0.75  (2)

2.3<f3/f<10.3  (3)

0.5<f1/f4<1.4  (4)

where f denotes focal length of the imaging lens overall optical system, f1, f3 and f4 denote focal lengths of the first, third and fourth lenses respectively, ih denotes maximum image height, and TTL denotes distance on the optical axis from the first lens object-side surface to the image plane.

Claims

1. An imaging lens which forms an image of an object on a solid-state image sensor, in which an F-value is 2.4 or less and elements are arranged in order from an object side to an image side, comprising:

a first lens with positive refractive power having a convex surface on the object side;

a second lens with negative refractive power having a concave surface on the image side;

a third lens with positive refractive power as a double-sided aspheric lens;

a fourth lens with positive refractive power having a convex surface on the image side; and

a fifth lens with negative refractive power as a double-sided aspheric lens having a concave surface on the image side, wherein

the image-side surface of the fifth lens has pole-change points off an optical axis; and

conditional expressions (1), (2), (3) and (4) below are satisfied;

0.80<

ih/f<

1.00 

 

(1)

0.6<

TTL/2ih<

0.75 

 

(2)

2.3<

f3/f<

10.3 

 

(3)

0.5<

f1/f4<

1.4 

 

(4)

where

f;

focal length of an overall optical system of the imaging lens

f1;

focal length of the first lens

f3;

focal length of the third lens

f4;

focal length of the fourth lens

ih;

maximum image height

TTL;

distance on the optical axis from the object-side surface of the first lens to an image plane.

2. The imaging lens according to claim 1,

wherein the fourth lens has an aspheric shape in which positive refractive power becomes weaker with increasing distance from the optical axis and changes to negative refractive power in the peripheral portion.

3. The imaging lens according to claim 1,

wherein a conditional expression (5) below is satisfied:

0.5<

f1/f<

1.0 

 

(5)

where

f;

focal length of the overall optical system of the imaging lens

f1;

focal length of the first lens.

4. The imaging lens according to claim 1,

wherein a conditional expression (6) below is satisfied:

−

1.6<

f2/f<

−

0.6 

 

(6)

where

f;

focal length of the overall optical system of the imaging lens

f2;

focal length of the second lens.

5. The imaging lens according to claim 1,

wherein a conditional expression (7) below is satisfied:

25<

ν

d1−

ν

d2<

40 

 

(7)

where

ν

d1;

Abbe number of the first lens at d-ray

ν

d2;

Abbe number of the second lens at d-ray.

6. The imaging lens according to claim 1,

wherein a conditional expression (8) below is satisfied:

−

0.9<

f5/f<

−

0.4 

 

(8)

where

f;

focal length of the overall optical system of the imaging lens

f5;

focal length of the fifth lens.

7. The imaging lens according to claim 1,

wherein a conditional expression (9) below is satisfied:

−

1.4<

(r1+r2)/(r1−

r2)<

−

0.3 

 

(9)

where

r1;

curvature radius of the object-side surface of the first lens

r2;

curvature radius of the image-side surface of the first lens.

8. The imaging lens according to claim 1,

wherein a conditional expression (10) below is satisfied:

0.75<

(r3+r4)/(r3−

r4)<

3.0 

 

(10)

where

r3;

curvature radius of the object-side surface of the second lens

r4;

curvature radius of the image-side surface of the second lens.

9. The imaging lens according to claim 1,

wherein a conditional expression (11) below is satisfied:

0.7<

(r7+r8)/(r7−

r8)<

1.8 

 

(11)

where

r7;

curvature radius of the object-side surface of the fourth lens

r8;

curvature radius of the image-side surface of the fourth lens.

10. The imaging lens according to claim 3,

wherein a conditional expression (9) below is satisfied:

−

1.4<

(r1+r2)/(r1−

r2)<

−

0.3 

 

(9)

where

r1;

curvature radius of the object-side surface of the first lens

r2;

curvature radius of the image-side surface of the first lens.

11. The imaging lens according to claim 4,

wherein a conditional expression (10) below is satisfied:

0.75<

(r3+r4)/(r3−

r4)<

3.0 

 

(10)

where

r3;

curvature radius of the object-side surface of the second lens

r4;

curvature radius of the image-side surface of the second lens.

12. The imaging lens according to claim 2,

wherein a conditional expression (11) below is satisfied:

0.7<

(r7+r8)/(r7−

r8)<

1.8 

 

(11)

where

r7;

curvature radius of the object-side surface of the fourth lens

r8;

curvature radius of the image-side surface of the fourth lens.